package com.rrd.hive.udf;
import java.util.BitSet;
import java.util.HashMap;
import com.weicai.caesar.CaesarUtil;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.hadoop.io.Text;

import java.security.NoSuchAlgorithmException;

//参考资料：https://blog.csdn.net/qq_31748587/article/details/84112740
@Description(
        name = "gps_geohash",
        value = "_FUNC_(lat,lon) - get blur str",
        extended = "Example:\n> SELECT _FUNC_(45,140);\n  yb0bh2n0p058\n> SELECT _FUNC_('45','140');\n  yb0bh2n0p058"
)
public class GPSTOGeohashUDF extends UDF {
    private static int numbits = 6 * 5; //经纬度单独编码长度
    //32位编码对应字符
    public final static char[] digits = { '0', '1', '2', '3', '4', '5', '6', '7', '8',
            '9', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', 'm', 'n', 'p',
            'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' };
    //定义编码映射关系
    final static HashMap<Character, Integer> lookup = new HashMap<Character, Integer>();
    //初始化编码映射内容
    static {
        int i = 0;
        for (char c : digits)
            lookup.put(c, i++);
    }
    //对编码后的字符串解码
    public double[] decode(String geohash) {
        StringBuilder buffer = new StringBuilder();
        for (char c : geohash.toCharArray()) {

            int i = lookup.get(c) + 32;
            buffer.append( Integer.toString(i, 2).substring(1) );
        }

        BitSet lonset = new BitSet();
        BitSet latset = new BitSet();

        //偶数位，经度
        int j =0;
        for (int i=0; i< numbits*2;i+=2) {
            boolean isSet = false;
            if ( i < buffer.length() )
                isSet = buffer.charAt(i) == '1';
            lonset.set(j++, isSet);
        }

        //奇数位，纬度
        j=0;
        for (int i=1; i< numbits*2;i+=2) {
            boolean isSet = false;
            if ( i < buffer.length() )
                isSet = buffer.charAt(i) == '1';
            latset.set(j++, isSet);
        }

        double lon = decode(lonset, -180, 180);
        double lat = decode(latset, -90, 90);

        return new double[] {lat, lon};
    }

    //根据二进制和范围解码
    private double decode(BitSet bs, double floor, double ceiling) {
        double mid = 0;
        for (int i=0; i<bs.length(); i++) {
            mid = (floor + ceiling) / 2;
            if (bs.get(i))
                floor = mid;
            else
                ceiling = mid;
        }
        return mid;
    }

    //对经纬度进行编码
    public String encode(double lat, double lon) {
        BitSet latbits = getBits(lat, -90, 90);
        BitSet lonbits = getBits(lon, -180, 180);
        StringBuilder buffer = new StringBuilder();
        for (int i = 0; i < numbits; i++) {
            buffer.append( (lonbits.get(i))?'1':'0');
            buffer.append( (latbits.get(i))?'1':'0');
        }
        return base32(Long.parseLong(buffer.toString(), 2));
    }

    //根据经纬度和范围，获取对应二进制
    private BitSet getBits(double lat, double floor, double ceiling) {
        BitSet buffer = new BitSet(numbits);
        for (int i = 0; i < numbits; i++) {
            double mid = (floor + ceiling) / 2;
            if (lat >= mid) {
                buffer.set(i);
                floor = mid;
            } else {
                ceiling = mid;
            }
        }
        return buffer;
    }

    //将经纬度合并后的二进制进行指定的32位编码
    private String base32(long i) {
        char[] buf = new char[65];
        int charPos = 64;
        boolean negative = (i < 0);
        if (!negative)
            i = -i;
        while (i <= -32) {
            buf[charPos--] = digits[(int) (-(i % 32))];
            i /= 32;
        }
        buf[charPos] = digits[(int) (-i)];

        if (negative)
            buf[--charPos] = '-';
        return new String(buf, charPos, (65 - charPos));
    }

    public Text evaluate(double lat, double lon) throws NoSuchAlgorithmException {
        Text text = new Text();
        try{
            text.set(encode(lat, lon));
        }catch (Exception ex){
            return null;
        }

        return text;
    }
    public Text evaluate(String lat, String lon) throws NoSuchAlgorithmException {
        Text text = new Text();
        try {

            text.set(encode(Double.valueOf(lat), Double.valueOf(lon)));
        }catch (Exception ex){
            return null;
        }

        return text;
    }

    public static void main(String[] args) throws Exception {
        GPSTOGeohashUDF udf = new GPSTOGeohashUDF();
        String s =udf.encode(22.558794, 121.999866);
        System.out.println(s);

    }
}
